Acute aortic dissection (AAD) classically manifests with sudden, severe chest pain radiating to the back or abdomen, often described as ripping or tearing sensation. Considering its abrupt onset, the diagnosis requires a high index of suspicion prompting immediate imaging using computed tomography (CT) with contrast. However, the use of contrast is a relative contraindication in the patients with renal compromise and acute care physicians are often deterred from contrast use in these patients. Herein, we present an unusual case of hematuria as the presenting symptom of a developing the Stanford type-A AAD...

Computed tomography coronary angiography (CTCA) has generated a great interest over the past two decades, due to its high diagnostic accuracy and efficacy in the assessment of patients having coronary artery disease. This method is associated with high radiation dose and this has raised serious concerns in the literature. Effective dose (E) is a single parameter meant to reflect the relative risk from exposure to ionizing radiation. Therefore, it is necessary to calculate this parameter to indicate ionizing radiation relative risk...

INTRODUCTION: Comprehensive clinical examination can be compromised in patients on veno-venous extracorporeal membrane oxygenation (VV-ECMO). Adjunctive diagnostic imaging strategies range from bedside imaging only to routine computed tomography (CT). The risk-benefit of either approach remains to be evaluated. Patients retrieved to the Royal Brompton Hospital (RBH) on VV-ECMO routinely undergo admission CT imaging of head, chest, abdomen and pelvis. This study aimed to identify how frequently changes in therapy or adverse events could be attributed to routine CT scanning...

We developed a novel technique to study the impact of geometric distortion of magnetic resonance imaging (MRI) on intensity-modulated radiation therapy treatment planning.&#13; The measured 3D datasets of residual geometric distortion (a 1.5-T MRI component of an MRI linear accelerator system) was fitted with a second-order polynomial model to map the spatial dependence of geometric distortions. Then the geometric distortion model was applied to computed tomography (CT) image and structure data to simulate the distortion of MRI data and structures...

INTRODUCTION: The risks of exposure to medical ionizing radiation is of increasing concern both among medical professionals and the general public. Patients with nephrolithiasis are exposed to high levels of ionizing radiation through both diagnostic and therapeutic modalities. Endourologists who perform a high-volume of fluoroscopy guided procedures are also exposed to significant quantities of ionizing radiation. The combination of judicious use of radiation-based imaging modalities, application of new imaging techniques such as ultra-low dose computed tomography (CT) scan, and modifying use of current technology such as increasing ultrasound and pulsed fluoroscopy utilization offers the possibility of significantly reducing radiation exposure...

BACKGROUND: Abdominal pain is a common reason patients seek treatment in emergency departments (ED), and computed tomography (CT) is frequently used for diagnosis; however, length of stay in the ED and risks of radiation remain a concern. The hypothesis of this study was the Alvarado Score (AS) could be used to reduce CT scans and decrease ED length of stay (LOS) for patients with suspected acute appendicitis (AA). METHODS: A retrospective review of patients who underwent CT to rule out AA from January 1st, 2015, to December 31st, 2015 was performed...

PURPOSE: To analyze the uncertainties of the rectum due to anisotropic shape variations by using a statistical point distribution model (PDM). MATERIALS AND METHODS: The PDM was applied to the rectum contours that were delineated on planning computed tomography (CT) and cone-beam CT (CBCT) at 80 fractions of 11 patients. The standard deviations (SDs) of systematic and random errors of the shape variations of the whole rectum and the region in which the rectum overlapped with the PTV (ROP regions) were derived from the PDMs at all fractions of each patient...

Distinctive patterns of early and late benign fibrosis are commonly observed after stereotactic ablative radiotherapy (SABR) for lung malignancies. These changes on computed tomographic scans need to be distinguished from so-called 'high-risk' radiological features, which can be associated with a higher risk for tumor recurrence. This pictorial report illustrates the different radiological changes seen following SABR delivered using the volumetric modulated radiotherapy, a technique which is increasingly used in clinical care...

X-rays are widely applied in the medical field for the diagnosis and treatment of diseases. Among the uses of X-rays in diagnosis, computed tomography (CT) has been established as one of the most informative diagnostic radiology examinations. Moreover, recent advances in CT scan technology have made this examination much easier and more informative and increased its application, especially in Japan. However, the radiation dose of CT scans is higher than that of simple X-ray examinations. Therefore, the health risk of a CT scan has been discussed in various studies, but is still controversial...

INTRODUCTION: The incidence of melanoma is increasing faster than any other major cancer both in Brazil and worldwide. The Southeast of Brazil has especially high incidences of melanoma, and early detection is low. Exposure to UV radiation represents a primary risk factor for developing melanoma. Increasing attractiveness is a major motivation for adolescents for tanning. A medical student-delivered intervention that harnesses the broad availability of mobile phones as well as adolescents' interest in their appearance may represent a novel method to improve skin cancer prevention...

PURPOSE: Distant metastasis (DM) is the main cause of death for patients with human papillomavirus (HPV)-related oropharyngeal cancers (OPCs); yet, there are few reliable predictors of DM in this disease. The role of quantitative imaging (ie, radiomic) analysis was examined to determine whether there are primary tumor features discernible on imaging studies that are associated with a higher risk of DM developing. METHODS AND MATERIALS: Radiation therapy planning computed tomography scans were retrieved for all nonmetastatic p16-positive OPC patients treated with radiation therapy or chemoradiation therapy at a single institution between 2005 and 2010...

BACKGROUND: The decision to obtain a computed tomography CT scan in the emergency department (ED) is complex, including a consideration of the risk posed by the test itself weighed against the importance of obtaining the result. In patients with limited access to primary care follow up the consequences of not making a diagnosis may be greater than for patients with ready access to primary care, impacting diagnostic reasoning. We set out to determine if there is an association between CT utilization in the ED and patient access to primary care...

PURPOSE: To develop a quality assurance (QA) tool that identifies inaccurate organ at risk (OAR) delineations. METHODS: The QA tool computed volumetric features from prior OAR delineation data from 73 thoracic patients to construct a reference database. All volumetric features of the OAR delineation are computed in 3-dimensional space. Volumetric features of a new OAR are compared with respect to those in the reference database to discern delineation outliers. A multi-criteria outlier detection system warns users of specific delineation outliers based on combinations of deviant features...

A PC Program for X ray Monte Carlo (PCXMC) has been used to calculate organ doses in patient dosimetry and for the exposure assessment in epidemiological studies of ra- diogenic health related risks. This study compared the dosimetry from using the built-in stylized phantoms in the PCXMC to that of a newer hybrid phantom library with improved anatomical realism. We simulated chest and abdominal x ray projections for 146 unique body size computational phantoms, 77 males and 69 females, with different combinations of height (125 - 180 cm) and weight (20 - 140 kg) using the built-in stylized phantoms in the PCXMC version 2...